Precision blend system

Need more help. Oil pump won't activate via engine sensor or toggle switch. Checked various pumps by switching back and forth with functioning starboard engine. (own twin Yami 1998 200s). Found harness and pump were bad, replaced them. Upon hookup, worked for a few days and stopped. went through trouble shooting literature sent by "just-in-time"; (thanks) Both sensors are good. Bypassed ground side (jumper wire directly to battery) no function, however, bypassed hot side (with ground side left connected through engine wiring) and pump functioned using toggle. Deduced ground side functioning properly, not getting power. Even switched the CDI unit, works fine on starboard engine but known working unit from starboard engine does not work on port side. Don't know where else to check. Unclear how power is routed. Wiring diagram from Seloc repair manual not clear. Appreciate some expertise, Tony D.

[boats.net]

Did you replace harnes between engine and remote oil tank, thats the one that gives trouble? Where are you connecting jumpers, at oil pump?

I replaced the harness from engine to remote oil tank, it definitely was bad. I jumped directly from oil pump on remote tank. Works fine connected directly to battery. Blue wire (ground) to black battery terminal and brown wire (hot) plugged in normally-no function. Brown hot wire jumped to red battery terminal and blue ground wire left plugged in normally, pump works with toggle; leading me to believe ground side with in-line toggle is OK, but power side is not functioning. Where, is the question. CDI unit worked fine on other engine.

[boats.net]

Test for 12 volts at brown wire at oil transfer pump(with key on), if no volts then test at engine oil harness connector. Should have ground at blue wire at oil transfer pump when toggle switch is in the on position, connect voltmeter to blue wire and battery positive post.

I'll try that, thanks.

Brown wire definitely not hot. Brown wire at engine harness (actually yellow at that point) not hot. Ground (blue) is 12 volts when connected to red batterey terminal and toggle on. Apparently not getting power to engine harness.